Special thanks to Dieter Scherk for providing this lens for testing purposes!

Introduction

The Zeiss Sonnar T* 135mm f/1.8 ZA (SAL-135F18Z) is the big brother of the recently reviewed ZA 85mm f/1.4 (SAL-85F14Z).
Obviously it offers a slightly longer reach by sacrificing a bit of speed. Citing Wikipedia: "The Sonnar is a photographic lens design originally patented by Carl Zeiss, notable for its relatively light weight, simple design and fast aperture. The name "Sonnar" is derived from the German word "Sonne", meaning sun. It was given this name because its large aperture (...)". The idea may be old but the Sonnar T* 135mm f/1.8 ZA is an all-new
design with no real ancestors - it takes advantage of 2x ED elements which is the most striking difference compared to the more conventional design of the ZA 85mm f/1.4. The Zeiss lens covers the full 35mm format where it
would be typically described as a lens with an emphasis on portrait photography. However, when used on an APS-C DSLR
the field-of-view is equivalent to about 203mm so it leaves that scope a little here due to the required camera-to-subject distance. Nonetheless it remains a highly interesting lens to isolate objects from their environment.

The build quality of the Zeiss lens is excellent also thanks to an all metal construction. The focus ring is decoupled from the AF gear so it does not rotate in AF mode. In manual focusing mode it operates very smooth but there is a little play when changing the focus direction - this is typical for non-SSM Sony lenses. The lens does not extend during
focusing operation which is different compared to the 85mm f/1.4. The front element does not rotate thanks to an IF (internal focusing) design. Unfortunately there're no seals against dust and humidity - something which should be standard in this lens and price class.

It is not a show-stopper but the AF system of the Zeiss lens does still rely on the rather outdated classic focusing system driven by the camera (via a slotted drive screw). Sony's modern SSM (supersonic motor) would have made more sense here. As a consequence of the conventional AF system the lens produces a moderate degree of noise during
operations. Due to the heavy weight of the lens system the AF speed is quite fine but not great.